<div class="refentry" lang="en" xml:lang="en"><a id="glActiveTexture"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glActiveTexture — select server-side active texture unit</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><table class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">glActiveTexture</b>(</code></td><td>GLenum <var class="pdparam">texture</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term">
                    <em class="parameter"><code>texture</code></em>
                </span></dt><dd><p>
                        Specifies which texture unit to make active. The
                        number of texture units is implementation dependent, but
                        must be at least two.
                        <em class="parameter"><code>texture</code></em> must be one of
                        <code class="constant">GL_TEXTURE</code><em class="replaceable"><code>i</code></em>,
                        where
                        <math overflow="scroll">
                            <mn>0</mn>
                            <mo>&lt;=</mo>
                            <mi>i</mi>
                            <mo>&lt;</mo>
                            <mi>GL_MAX_TEXTURE_UNITS</mi>
                        </math>,
                        which is an implementation-dependent value. The intial value is
                        <code class="constant">GL_TEXTURE0</code>.
                    </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
        <code class="function">glActiveTexture</code>
        selects which texture unit subsequent texture state calls will
        affect. The number of texture units an implementation supports
        is implementation dependent, it must be at least 2.</p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p>
            <code class="constant">GL_INVALID_ENUM</code> is generated if
            <em class="parameter"><code>texture</code></em> is not one of
            <code class="constant">GL_TEXTURE</code><em class="replaceable"><code>i</code></em>,
            where
            <math overflow="scroll">
                <mn>0</mn>
                <mo>&lt;=</mo>
                <mi>i</mi>
                <mo>&lt;</mo>
                <mi>GL_MAX_TEXTURE_UNITS</mi>
            </math>.
        </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p>It is always the case that
        <math overflow="scroll">
            <mi>GL_TEXTURE</mi><mi>i</mi> <mo>=</mo>
            <mi>GL_TEXTURE0</mi><mo>+</mo><mi>i</mi>
        </math>.</p><p>A texture unit consists of the texture enable state,
            texture matrix stack, texture environment and currently bound
            texture. Modifying any of these states has an effect only on
            the active texture unit.
        </p><p>Vertex arrays are client-side GL resources, which are
        selected by the
        <a class="citerefentry" href="glClientActiveTexture"><span class="citerefentry"><span class="refentrytitle">glClientActiveTexture</span></span></a>
        routine.</p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
            <a class="citerefentry" href="glGet"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a>
            with argument <code class="constant">GL_ACTIVE_TEXTURE</code> or
            <code class="constant">GL_MAX_TEXTURE_UNITS</code>
        </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
            <a class="citerefentry" href="glBindTexture"><span class="citerefentry"><span class="refentrytitle">glBindTexture</span></span></a>,
            <a class="citerefentry" href="glClientActiveTexture"><span class="citerefentry"><span class="refentrytitle">glClientActiveTexture</span></span></a>,
            <a class="citerefentry" href="glEnable"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a>,
            <a class="citerefentry" href="glGet"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a>,
            <a class="citerefentry" href="glMatrixMode"><span class="citerefentry"><span class="refentrytitle">glMatrixMode</span></span></a>,
            <a class="citerefentry" href="glMultiTexCoord"><span class="citerefentry"><span class="refentrytitle">glMultiTexCoord</span></span></a>,
            <a class="citerefentry" href="glTexEnv"><span class="citerefentry"><span class="refentrytitle">glTexEnv</span></span></a>
        </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="copyright"></a><h2>Copyright</h2><p>
            Copyright © 2003-2004
            Silicon Graphics, Inc. This document is licensed under the SGI
            Free Software B License. For details, see
            <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
        </p></div></div>
